A US film that insults the Prophet Mohammed is set to spark more unrest as demonstrations are planned across the Muslim world.

The Muslim Brotherhood is calling for a million-man march in the Egyptian capital Cairo after Friday prayers as anger against a film mocking the Prophet Mohammed spreads across the Middle East.

Police have built a wall across the road to the US Embassy with huge concrete blocks as running battles continue between protesters and police.

In Cairo, said protesters have been throwing stones and lighting fires and police have been trying to clear the crowds with tear gas.

Protesters, some bearded Islamists wearing traditional robes, but most young men in T-shirts and jeans, attacked a line of police blocking their way to the fortified US compound near Tahrir Square.

A burnt-out car was overturned in the middle of the street.

Ramsay said most of the stone-throwing protesters were young men in their late teens, but they had now been joined by the first of the organised rallies held to complain about the US-made film.

The video, being promoted on YouTube, depicts the Prophet Mohammed having sex, calling for massacres, and as a homosexual.

In Yemen, security forces have also blocked streets surrounding the US embassy in Sanaa, a day after demonstrators stormed the compound.

Local media said US marines had flown into Sanaa’s international airport on Thursday to bolster the embassy’s security.

At least one person died and 15 were injured during Thursday’s demonstration. Yemen’s President Abd-Rabbu Mansour Hadi condemned the attack.

Demonstrations are also due to take place in Sudan, after state-backed Islamic scholars urged people to “defend Prophet Mohammed”.

Riot policemen throw stones and release tear gas during clashes with protesters along a road which leads to the U.S. embassy, near Tahrir Square in Cairo

Salah el Din Awad, general secretary of the scholars’ group in Khartoum state, said: “We have 5,000 mosques in Khartoum with two million people attending Friday prayers. We will all go out to defend Prophet Mohammed. We will do this peacefully but with strength.”

Religious clerics in Pakistan joined calls for a day of protests, while further demonstrations are likely to continue in countries including Kuwait, Tunisia, and Morocco.

Britain’s Defence Secretary Philip Hammond has raised concerns about the potential for the unrest to spread to Afghanistan. In a newspaper interview, he said security is being boosted around British bases.

The violence followed Tuesday night’s storming of the US Consulate and a safe house in Benghazi, Libya, in which the US ambassador to Libya, Chris Stevens, and three other American officials were killed.

President Barack Obama said the perpetrators would be tracked down and ordered two destroyers to head to the Libyan coast.

Eastern Libya’s deputy interior minister, Wanis el Sharef, said the film protests were a cover for a violent assault planned to coincide with the 11th anniversary of the September 11 terror attacks.